There are three main types of glacial erosion – plucking, abrasion and freeze thaw.

Three types of glacial erosion, freeze-thaw, plucking and abrasion.

Plucking is when melt water from a glacier freezes around lumps of cracked and broken rock. When the ice moves downhill, rock is plucked from the back wall. Abrasion is when rock frozen to the base and the back of the glacier scrapes the bed rock. Freeze-thaw is when melt water or rain gets into cracks in the bed rock, usually the back wall. At night the water freezes, expands and causes the crack to get larger. Eventually the rock will break away.